Recently, optical recording media are attracting attention since a great amount of information can be recorded and are used in various applications. Methods for three dimensionally recording data are proposed to further increase the density of recording.
For example, in Patent Reference 1, a recording method in which laser light is concentrated on a photosensitive material, data are written three dimensionally as changes in the refractive index, and the recorded data are read using a confocal microscope of the reflection type, is disclosed. As the optical recording medium used for the above recording method, a multilayer optical recording medium in which a photorefractive material such as lithium niobate, a photochromic coloring matter giving reversible structural change with light such as a diarylethene and spiropyran, a compound giving photoisomerization such as azobenzene and stilbene, a substance obtained by modifying a macromolecular structure with the above coloring matter or compound or a combination of an agent which absorbs two photons and generates an acid with light and a coloring matter developing color with the acid is used for the optical recording layer, and a non-recording layer comprising a material which cannot record information with light is introduced between the optical recording layers to decrease crosstalk, is proposed (refer to Patent Reference 2).
It has been found by the present inventors that the multilayer optical recording medium having the structure described above can be produced with excellent productivity by using a pressure sensitive adhesive sheet in which an optical recording layer and a layer of a pressure sensitive adhesive as the non-recording layer are laminated (refer to Patent Reference 3).
It is proposed that, in the multilayer optical recording medium described above, positional information specifically describing the position in the three dimensional space is contained at the inside of the optical recording medium (refer to Patent Reference 4). In the method of laminating sheets comprising an optical recording layer and a layer of a pressure sensitive adhesive, it has been difficult that the positional information described above is contained.
[Patent Reference 1] Japanese Patent Application Laid-Open No. Heisei 6(1994)-28672
[Patent Reference 2] Japanese Patent Application Laid-Open No. Heisei 11(1999)-250496
[Patent Reference 3] Japanese Patent Application Laid-Open No. 2005-209328
[Patent Reference 4] Japanese Patent Application Laid-Open No. 2005-285211